Variable Field Proton-Electron Double-Resonance Imaging: Application to pH mapping of aqueous samples.

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Spectroscopy

Background:

• Functional mapping with MRI typically requires specialized probes.
• Paramagnetic probes offer potential for enhanced MRI contrast and functional information.
• Proton-Electron Double-Resonance Imaging (PEDRI) combines MRI and Electron Paramagnetic Resonance (EPR) principles.

Purpose of the Study:

• To introduce and validate a novel Variable Field Proton-Electron Double-Resonance Imaging (VF PEDRI) technique.
• To demonstrate the capability of VF PEDRI for functional mapping of biological parameters.
• To assess the spatial and resolution capabilities of VF PEDRI for pH mapping.

Main Methods:

• Development of the Variable Field Proton-Electron Double-Resonance Imaging (VF PEDRI) concept.
• Acquisition of two PEDRI images at pre-selected EPR excitation fields using a 200 G MRI system.
• Utilizing specifically designed paramagnetic probes for targeted parameter mapping.

Main Results:

• Successful pH mapping of a sample was achieved using VF PEDRI.
• The technique provided a pH resolution of 0.1 pH units.
• A spatial resolution of 1.25 mm was obtained with an acquisition time of 140 seconds.

Conclusions:

• VF PEDRI is a promising technique for high-resolution functional MRI.
• The method allows for rapid mapping of pH and potentially other biologically relevant parameters like oxygen and redox state.
• This approach enhances MRI capabilities for studying dynamic biological processes.